1. Field of the Invention
This invention relates generally to access sealing devices and more specifically to surgical devices and methods providing a working channel for the insertion of instrumentation across a body wall and into a body cavity.
2. Discussion of the Relevant Art
Access devices in general are disposed relative to a conduit and are adapted to provide input to a flow of fluid through the conduit. The device will typically include a valve assembly which controls passage of the fluid in either a liquid state or a gas state. Such access devices might be adapted for use with fluids such as foods, oils, and grease, for example.
Devices of particular interest include surgical access devices which are commonly used to form a passage way across a body wall and into a body conduit or other body cavity.
This passageway enables a surgeon operating exteriorly of the body to perform surgical operations within the body cavity by manipulating instruments through the passageway. These instruments might include scopes, needles, graspers, clamps, staplers, sutures, and cutters, for example.
Of course the passageway, more commonly referred to as a working channel, also provides a path for fluids to exit the body from the body cavity. In order to inhibit this leakage of fluids, some access devices are provided with valves which can seal the working channel both in the absence of an instrument and in the presence of an instrument.
The sealing of the working channel is of particular importance in the case of laparoscopic surgeries where the abdominal cavity is inflated with an insufflation gas in order to distend the abdominal wall and thereby increase the size of the working environment. Trocars are commonly used as access devices for this type of surgery. The trocars include a cannula and a seal housing containing one or more valves which facilitate instrument access while inhibiting leakage of the insufflation gas.
In the past, trocar valves have typically included at least one zero valve intended to form a zero seal in the absence of an instrument, and at least one instrument valve intended to form an instrument seal in the presence of an instrument. Zero seals have typically been formed by duckbill seals which are incapable of also functioning as an instrument seal. The instrument seals have typically been formed by septum valves, having a hole or opening which is radially stretchable to some limited extent. With the limited stretchability of the septum valves, the trocars of the past have been able to accommodate only a small range of instrument diameters.
Due to this limited accommodation of instrument sizes, different trocars have been required in order to accommodate a full range of instrument sizes from almost zero mm to 12 mm. In some cases a smaller trocar would be used initially only to find that a larger instrument was required. In these instances, the smaller trocar had to be completely removed in order to inset a larger trocar to accommodate the larger instrument. As a result, a whole set of trocars, each having a different septum valve were required. Eventually, single trocars were provided having multiple septum valves of different sizes, along with a zero valve for each of the septum valves. Of course these instruments were much more complex and expensive.
In the past, septum valves were positioned along the axis of the working channel. However, it was observed that instrument seals would tend to leak if the instrument was moved off-axis. Accordingly, septum valves were provided with floating characteristics whereby the seal interface could be maintained even if the instrument was positioned off-axis. Of course, this floating of the septum seal required special structure which increased the cost of manufacture.
Septum valves have also been highly susceptible to tearing, particularly by instruments having sharp points. Elaborate guiding and protection mechanisms were provided to protect the septum seals against this type of instrument. Again, the sophisticated protection structures significantly increased the complexity of the device and the resulting cost of manufacture.